Conventional semiconductor chip-assembly processes begin with die-bonding where individual integrated circuit (IC) die having a plurality of interconnected circuit elements are separated from a wafer, which are then attached to the die pad of a leadframe by a die-bonding apparatus. The leadframes are part of a large leadframe sheet (or leadframe panel) including a 2-dimensional array of leadframes.
A leadframe transport apparatus including side rails is generally used for transporting the leadframes sheets through to the die-bonding apparatus and wire bonding apparatus. After wire bonding, the individual leadframes are electrically coupled to the IC die by bond wires or by directly bonding parts thereof to metal bond pads on the IC die using a wire bonding apparatus to form IC die assemblies. The IC die assemblies are then encapsulated to provide protection from environmental effects, such as moisture, and electrical shock. The packaged IC is then subjected to a cutting/forming process to cut and form the leads to adapt the package for mounting on a circuit board.
FIG. 1 is a perspective view of a conventional leadframe transport apparatus 100 including two rails including a first rail 150a and second rail 150b, having mechanical clampers 172. The rails 150a and 150b have the same structure. The width (W) of the machine track 160 defined by the spacing of the rails 150a and 150b is adjustable, depending on the W of the leadframe sheet (LDF) 116 which is to be transported.
Machine pusher 144 is shown for translating the LDF 116 from left to right in FIG. 1. As known in the art, other mechanisms for moving the LDF 116 include conveyor belts and a mobile base. When the LDF 116 reaches certain predetermined position(s) along the rails 150a/150b, a position sensor (not shown) detects the position of LDF 116 and a controller transmits a detection signal to an actuator which actuates the mechanical clamper (or stopper) 172 shown on rails 150a and 150b. The mechanical clamper 172 includes a feature which when actuated is projected downward that engages (contacts) the LDF 116 directly resulting in stopping the movement of the LDF 116. Since the moving and stopping of the LDF 116 is controlled by a controller, the machine pusher 144 can be depressed (so that it no longer pushes the LDF 116) when the mechanical clamper 172 is engaging (contacting) the LDF 116.
Conventional leadframe transport apparatus 100 has certain problems associated with the operation of the mechanical clamper 172. For example, the LDF 116 can miss a required transfer if the mechanical clamper 172 does not engage properly. Adjustments for proper function of the mechanical clamper 172 are known to be needed when material issues of the LDFs are found, such as in the case of a warped LDF 116. Adjustments are made manually, are known to be difficult, and can cause significant down time. If the mechanical clamper 172 is adjusted too tight, the LDF 116 can jam and as a result can be damaged. If the mechanical clamper 172 is adjusted too loose, the LDF 116 can fail to stop at its required position which can cause machine error. Due to the potential for jamming of the LDF 116, the translation speed utilized by conventional leadframe transport apparatus 100 reflected in its throughput generally measured in units per hour (UPH) can be significantly limited.